Document ES 0215567 A3 relates to a ratchet wrench that comprises a head provided with a pair of clamps, a handle connected to the head capable of relative rotation around a hinge axis, and a ratchet mechanism that includes a ratchet wheel section coaxial to said hinge axis, integrally formed with the head body and provided with circumferential teeth along part of a peripheral edge thereof, a ratchet pawl movably installed on the handle, and an elastic element which biases said ratchet pawl against said circumferential teeth of the ratchet wheel. The wrench additionally includes a releasing member movably installed on the handle and linked to the ratchet pawl so that when the releasing member is manually moved from a rest position to a release position, the ratchet pawl is disengaged from the ratchet wheel against the bias of said elastic working element.
A drawback of the ratchet wrench from the referenced document ES 0215567 A3 is that the releasing member is rigidly connected to the ratchet pawl, and, consequently, the movements that the ratchet pawl inevitably experiences when, during its operation, it jumps from one tooth to another of the circumferential teeth of the ratchet wheel, are transmitted to the releasing member, which can cause unnecessary noise and inconvenience to the user that is gripping the tool by the handle. Another drawback is that the ratchet pawl is provided with guided linear movements in a direction aligned with the hinge axis and has a single tooth that engages the circumferential teeth of the ratchet wheel in a radial direction, which is hardly prone to resisting the tangential stresses experienced by the ratchet mechanism when operating in the retention direction.
Document US 20060225539 A1 relates to a wrench provided with a handle attached to a head with two movable clamps through a driving mechanism that comprises a driving screw rotatably mounted on the head body and provided with two externally threaded portions with opposite threading directions respectively engaged to corresponding internally threaded holes with opposite threading directions formed on both clamp bodies, respectively. On both ends of the driving screw respective gripping elements are fixed arranged in positions accessible to be gripped and turned by a user.
A drawback of the wrench from referenced document US 20060225539 A1 is that the material of both clamp bodies surrounding by 360° the respective internally threaded holes occupies a relatively large space in the head body, and this space, in case one wishes to connect the handle with the head by means of a ratchet mechanism, it would force one to provide a ratchet wheel with a relatively small diameter or to place the hinge axis relatively far from the clamps, both options being unfavourable as regards the mechanical performance of the components and the versatility of the tool. Another drawback is that it includes a retention device located in a central position that prevents the complete closure of the clamps.